The invention relates to a brake device of an elevator car that, at least on occurrence of an inadmissibly high speed of the elevator car, brakes the elevator car.
From JP 06092568 such a brake device is known, in which an overspeed governor with a rope sheave activates via an overspeed governor rope a brake unit on an elevator car. In the form of a closed loop, the overspeed governor rope passes at one end round the rope sheave of the overspeed governor that is arranged in the upper area of the car travel path, and at the other end round a rope reversing sheave that is present in the lower area of the car travel path. One end of the rope loop is coupled to an actuating element of the brake unit that is mounted on the elevator car, and therefore also to the elevator car. The lower rope reversing sheave is arranged vertically movable and loaded in downward direction by a weight, so that the rope loop is tensioned by the lower rope reversing sheave. A monitoring device with a detector monitors the position of this lower rope reversing sheave so as to influence the elevator control system in case of breakage, or excessive elongation, of the overspeed governor rope.
In the mentioned state of the art, breakage or excessive elongation of the overspeed governor rope is detected by a detector, and corresponding safety measures initiated if necessary. However, failure of the coupling between the overspeed governor rope and the elevator car during operation of the elevator is not detected by the monitoring device. This has the consequence that, on failure of the coupling, the elevator system remains in operation even though the brake device on the elevator car, that is of utmost importance for the safety of the passengers, is not functioning.
Possible causes of such failure of the coupling between the overspeed governor rope and the brake unit, and thereby also the elevator car are, for example, a fallen-out or fractured connecting bolt, a fractured actuating lever (actuating element) of the brake unit, or a broken actuating shaft via which the actuating lever is connected to the brake unit and thereby also the elevator car.